Chapter 8Section 2 Igneous and Sedimentary Rocks
Igneous Rocks Rocks are made of different minerals. Minerals: solid, inorganic substance Igneous rocks -created by melted material called magma or lava as it cools. Two types: Extrusive and Intrusive.
Chemical Composition The chemicals in the melted rock material determine the color of the resulting rock.
Extrusive Extrusive igneous rock form when melted rock material cools on Earth’s surface Form in two ways: - volcanic eruption - fissures on Earth’s crust
Extrusive Igneous Rocks Granitic (gra NIH tihk) rock are light color. Extrusive igneous rocks are often granitic. .
Intrusive Intrusive : igneous rockforms when the melted rock material cools below Earth’s surface.
Rocks from Magma Intrusive igneous rocks form when huge glob of magma from inside Earth is forced upward toward the surface but never reaches it.
Rocks from Magma The magma stays underneath the Earth’s surfaces cooling for millions of years. This allows for minerals in the magma to form crystals. This is why most intrusive igneous rocks have large crystals.
Sedimentary Rocks Sedimentary rocks: are a type of rock made from pieces of other rocks, dissolved minerals, or plant and animal matter that collect to form rock layers. How do you think they form or break apart? - wind, waves, rivers, etc. & then it is deposited to form rock
Three Types of Sedimentary Rock Examples: Detrital, Chemical, and Organic rocks All these types of sedimentary rocks can be created from igneous, metamorphic and even more sedimentary rocks.
Type 1: Detrital Detrital Rocks: are a type of sediment. made out of grains of minerals or other rocks that have moved and been deposited in layers by water, ice, gravity or wind.
Identifying Detrital Rocks Detrital rocks can be identify by the size of the grains that make up the rock. Shale, siltstone, sandstone and pebbles are all different types of Detrital rocks.
Conglometrates: Ditrital Pebbles mixed with other sediment and create a rock called conglomerates.
Type 2: Chemical Rocks Another type of sedimentary rocks are rocks that have formed from evaporation or other chemical process, these are chemical rocks.
Chemical Sedimentary Rocks Chemical sedimentary rocks form when seawater loaded with dissolved mineral evaporates. Chemical sedimentary rocks also forms when mineral-rich water from geysers, hot springs, or salty lakes evaporates. As the water evaporates, layers of the minerals are left behind.
Type 3: Organic Rocks Organic rocks are another type of sedimentary rocks that contain pieces of things that were once alive. These pile up -> compress -> Rock! Formed on land: Coal Formed in the ocean: Limestone
Fossils A fossil is the remains or trace of a once-living plant, animal, or microbe. Fossils are type of limestone that is made up over millions of years from these organisms. Fossils can be found in all three types of sedimentary rocks – detrital, chemical, and organic.